U.S. patent application number 10/473470 was filed with the patent office on 2004-06-24 for electroluminescence device.
Invention is credited to Ashida, Tsuyoshi, Takahashi, Kenji.
Application Number | 20040119400 10/473470 |
Document ID | / |
Family ID | 27573749 |
Filed Date | 2004-06-24 |
United States Patent
Application |
20040119400 |
Kind Code |
A1 |
Takahashi, Kenji ; et
al. |
June 24, 2004 |
Electroluminescence device
Abstract
A dispersion electroluminescence device having a basic
constitution wherein a back face sheet, a back-face side
light-transmitting electrode, a luminescent layer with
electroluminescence light-emitting particles dispersed in a
dielectric phase, a front-face side light-transmitting electrode,
and a light-transmitting front face protecting film are stacked in
this order. The utilization of the constitution of the
electroluminescence device the back face sheet of which has the
performance of light scattering reflection and the light emitting
layer of which shows the performance of light scattering provides
an electroluminescence (EL) device enhanced in the efficiency of
extracting emitted light outside.
Inventors: |
Takahashi, Kenji; (Kanagawa,
JP) ; Ashida, Tsuyoshi; (Kanagawa, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Family ID: |
27573749 |
Appl. No.: |
10/473470 |
Filed: |
September 29, 2003 |
PCT Filed: |
March 29, 2002 |
PCT NO: |
PCT/JP02/03226 |
Current U.S.
Class: |
313/504 |
Current CPC
Class: |
H05B 33/02 20130101;
C09K 11/025 20130101; H05B 33/20 20130101; H05B 33/14 20130101;
H05B 33/12 20130101; C09K 11/574 20130101; H05B 33/22 20130101;
C09K 11/02 20130101 |
Class at
Publication: |
313/504 |
International
Class: |
H01J 001/62; H05B
033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2001 |
JP |
2001-97510 |
Mar 29, 2001 |
JP |
2001-97511 |
Mar 29, 2001 |
JP |
2001-97517 |
Sep 26, 2001 |
JP |
2001-293442 |
Sep 26, 2001 |
JP |
2001-293448 |
Sep 27, 2001 |
JP |
2001-298416 |
Sep 27, 2001 |
JP |
2001-298421 |
Sep 28, 2001 |
JP |
2001-301596 |
Claims
Scope of claims:
1. A dispersion electroluminescence device comprising a back face
sheet, a light-transmitting back electrode, a light-emitting layer
comprising electroluminescence light-emitting particles dispersed
in a dielectric material phase, a light-transmitting front
electrode, and a light-transmitting front protecting film arranged
in order, wherein the back face sheet shows a light-scattering
reflective property and the light-emitting layer shows a
light-scattering property.
2. The electroluminescence device of claim 1, wherein the
electroluminescence light-emitting particle comprises a phosphor
particle coated with a coat layer.
3. The electroluminescence device of claim 2, wherein the coat
layer has a refractive index of 65% or higher based on a refractive
index of the phosphor particle.
4. The electroluminescence device of claim 2 or 3, wherein the
dielectric material phase of the light-emitting layer has a
refractive index of 65% or higher based on a refractive index of
the phosphor particle.
5. The electroluminescence device of one of claims 1 through 4,
wherein the dielectric material phase comprises inorganic or
organic fine particles dispersed in organic polymer.
6. A dispersion electroluminescence device comprising a back face
sheet, a back electrode, a light-emitting layer comprising
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the electroluminescence light-emitting particle comprises a
dielectric material particle coated with a phosphor layer which is
further coated with an outer coat layer.
7. The electroluminescence device of claim 6, wherein the
dielectric material phase comprises an organic polymer.
8. The electroluminescence device of claim 6, wherein the
dielectric material phase comprises inorganic or organic fine
particles dispersed in an organic polymer.
9. The electroluminescence device of claim 7 or 8, wherein the
light-emitting layer shows a light scattering property.
10. The electroluminescence device of one of claims 7 through 9,
wherein the back electrode is a light-transmitting electrode and
the back face sheet shows a light-scattering reflective
property.
11. The electroluminescence device of one of claims 7 through 10,
wherein the outer coat layer of the electroluminescence
light-emitting particle has a refractive index of 65% or higher
based on a refractive index of the phosphor layer of the
light-emitting particle.
12. The electroluminescence device of one of claims 7 through 11,
wherein the dielectric material phase of the light-emitting layer
has a refractive index of 65% or higher based on a refractive index
of the phosphor layer of the light-emitting particles.
13. The electroluminescence device of one of claims 7 through 12,
wherein the back electrode is a light-transmitting electrode, the
back face sheet is a light-scattering reflective, high refraction
sheet which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the phosphor layer of the electroluminescence light-emitting
particle, and a refractive index of material placed between the
electroluminescence light-emitting particles and the back face
sheet is adjusted, whereby 40% or more of a light emitted by the
light-emitting particles toward a back side enters the back face
sheet.
14. The electroluminescence device of one of claims 7 through 13,
wherein the back electrode is a light-transmitting electrode, the
back face sheet shows a light-scattering reflective property, a
light-scattering, high refraction layer comprising as main
component a material having a refractive index of 80% or higher
based on a refractive index of the phosphor layer of the
electroluminescence light-emitting particle is placed between the
front electrode and the front protecting film, and a refractive
index of material placed between the light-emitting particles and
the light-scattering, high refraction layer is adjusted, whereby
40% or more of a light emitted by the electroluminescence
light-emitting particles toward a front side enters the
light-scattering, high refraction layer.
15. A dispersion electroluminescence device comprising a back face
sheet, a back electrode, a light-scattering or non
light-scattering, light-emitting layer which comprises
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the electroluminescence light-emitting particle comprises a
dielectric material particle coated with a phosphor layer.
16. The electroluminescence device of claim 15, wherein the back
electrode is a light-transmitting electrode and the back face sheet
shows a light-scattering reflective property.
17. The electroluminescence device of claim 15 or 16, wherein the
dielectric material phase has a refractive index of 65% or higher
based on a refractive index of the phosphor layer of the
electroluminescence light-emitting particle.
18. The electroluminescence device of one of claims 15 through 17,
wherein the dielectric material particle has a dielectric constant
of as much as 3 times or more based on a dielectric constant of the
phosphor layer of the electroluminescence light-emitting
particle.
19. The electroluminescence device of one of claims 15 through 18,
wherein the back electrode is a light-transmitting electrode, the
back face sheet is a light-scattering reflective, high refraction
sheet which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the phosphor layer of the electroluminescence light-emitting
particle, and a refractive index of material placed between the
light-emitting particles and the back face sheet is adjusted,
whereby 40% or more of a light emitted by the electroluminescence
light-emitting particles toward a back side enters the back face
sheet.
20. The electroluminescence device of one of claims 15 through 19,
wherein the back electrode is a light-transmitting electrode, the
back face sheet shows a light-scattering reflective property, a
light-scattering, high refraction layer which comprises as main
component a material having a refractive index of 80% or higher
based on a refractive index of the phosphor layer of the
electroluminescence light-emitting particle is placed between the
front electrode and the front protecting film, and a refractive
index of material placed between the light-emitting particles and
the light-scattering, high refraction layer is adjusted, whereby
40% or more of a light emitted by the electroluminescence
light-emitting particles toward a front side enters the
light-scattering, high refraction layer.
21. A dispersion electroluminescence device comprising a back face
sheet, a light-transmitting back electrode, a light-emitting layer
comprising electroluminescence light-emitting particles dispersed
in a dielectric material phase, a light-transmitting front
electrode, and a light-transmitting front protecting film arranged
in order, wherein the back face sheet shows light reflection by a
light-scattering effect, a light-scattering, high refraction layer
which comprises as main component a material having a refractive
index of 80% or higher based on a refractive index of the
electroluminescence light-emitting layer is placed between the
light-transmitting front electrode and the front protecting film,
and a refractive index of material placed between the
light-emitting layer and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a front side enters
the light-scattering, high refraction layer.
22. The electroluminescence device of claim 21, wherein an
insulating material layer is placed between the electroluminescence
light-emitting layer and the light-transmitting front electrode
and/or the light-transmitting back electrode.
23. The electroluminescence device of claim 21 or 22, wherein the
light-scattering, high refraction layer comprises as main component
a material having a refractive index of 95% or higher, based on the
refractive index of the electroluminescence light-emitting layer,
and the refractive index of material placed between the
light-emitting layer and the light-scattering, high refraction
layer is adjusted, whereby 70% or more of a light emitted by the
light-emitting layer toward a front side enters the
light-scattering, high refraction layer.
24. A dispersion electroluminescence device comprising a back face
sheet, a light-transmitting back electrode, an electroluminescence
light-emitting layer comprising electroluminescence light-emitting
particles dispersed in a dielectric material phase, a
light-transmitting front electrode, and a light-transmitting front
protecting film arranged in order, wherein the back face sheet is a
light-scattering reflective, high refraction sheet which comprises
as main component a material having a refractive index of 80% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and a refractive index of material placed
between the light-emitting layer and the back face sheet is
adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a back side enters
the back face sheet.
25. The electroluminescence device of claim 24, wherein an
insulating material layer is placed between the electroluminescence
light-emitting layer and the light-transmitting front electrode
and/or the light-transmitting back electrode.
26. The electroluminescence device of claim 24 or 25, wherein a
light-scattering, high refraction layer which comprises as main
component a material having a refractive index of 80% or higher
based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
27. A dispersion electroluminescence device comprising a back face
sheet, a back electrode, a back insulating material layer, an
electroluminescence light-emitting layer comprising
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode, a
light-transmitting front protecting film arranged in order, wherein
the back insulating material layer is a light-scattering, high
refraction, insulating material layer which comprises as main
component a material having a refractive index of 80% or higher
based on a refractive index of the electroluminescence
light-emitting layer, and 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a back side enters
the back insulating layer.
28. The electroluminescence device of claim 27, wherein the back
face sheet shows light reflection by a light-scattering effect and
the back electrode is a light-transmitting electrode.
29. A dispersion electroluminescence device comprising a back face
sheet, a light-transmitting back electrode, an electroluminescence
light-emitting layer comprising electroluminescence light-emitting
particles dispersed in a dielectric material phase, an front
insulating material layer, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the back face sheet shows light reflection by a
light-scattering effect, the front insulating material layer is a
light-scattering, high refraction, insulating material layer which
comprises as main component a material having a refractive index of
80% or higher, based on a refractive index of the
electroluminescence light-emitting layer, and 40% or more of a
light emitted by the electroluminescence light-emitting layer
toward a front side enters the front insulating material layer.
30. A dispersion electroluminescence device comprising a back face
sheet, a back electrode, a back insulating material layer, an
electroluminescence light-emitting layer comprising
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the back insulating material layer has a thickness of 10
.mu.m or more and is a light-scattering, high refraction,
insulating material layer having a diffuse reflectance of 50% or
higher.
31. The electroluminescence device of claim 30, wherein the diffuse
reflectance of the back insulating material layer is 70% or
higher.
32. The electroluminescence device of claim 30 or 31, wherein the
thickness of the back insulating material layer is in the range of
10 to 100 .mu.m.
33. An electroluminescence device comprising a back face sheet, a
back electrode, a back insulating material layer, an
electroluminescence light-emitting layer, a light-transmitting
front electrode, and a light-transmitting front protecting film
arranged in order, wherein the back insulating material layer has a
thickness of 10 .mu.m or more and is a light-scattering, high
refraction, insulating material layer having a diffuse reflectance
of 50% or higher.
34. The electroluminescence device of claim 33, wherein an
insulating material layer is placed on a front side of the
electroluminescence light-emitting layer.
35. The electroluminescence device of claim 33, wherein the diffuse
reflectance of the back insulating material layer is 70% or
higher.
36. The electroluminescence device of claim 33 or 35, wherein the
thickness of the back insulating material layer is in the range of
10 to 100 .mu.m.
37. The electroluminescence device of one of claims 33 through 36,
wherein the electroluminescence light-emitting layer is made of a
thin phosphor film.
38. An electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet is a light-scattering reflective, high
refraction sheet comprising as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer, and a refractive
index of material placed between the light-emitting layer and the
back face sheet is adjusted, whereby 40% or more of a light emitted
by the electroluminescence light-emitting layer toward a back side
sheet enters the back face sheet.
39. The electroluminescence device of claim 38, wherein an
insulating material layer is placed on a front side and/or a back
side of the electroluminescence light-emitting layer.
40. The electroluminescence device of claim 38, wherein a
light-scattering, high refraction layer which comprises as main
component a material having a refractive index of 80% or higher
based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
41. An electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, a back insulating material
layer, an electroluminescence light-emitting layer, a
light-transmitting front electrode, and a light-transmitting front
protecting film arranged in order, wherein the back face sheet
shows light-scattering reflection, the back insulating material
layer is a light-scattering, high refraction, insulating material
layer which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer, and 40% or more of a
light emitted by the electroluminescence light-emitting layer
toward a back side enters the back insulating material layer.
42. The electroluminescence device of claim 41, wherein an
insulating material layer is placed on a front side of the
electroluminescence light-emitting layer.
43. An electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction layer comprising as
main component a material having a refractive index of 80% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
44. The electroluminescence device of claim 43, wherein an
insulating material layer is placed on a front side and/or a back
side of the electroluminescence light-emitting layer.
45. An electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction, insulating material
layer comprising as main component a material having a refractive
index of 80% or higher based on a refractive index of the
electroluminescence light-emitting layer is placed on a front side
of the electroluminescence light-emitting layer, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction, insulating material layer.
46. The electroluminescence device of claim 45, wherein an
insulating material layer is placed on a back side of the
electroluminescence light-emitting layer.
47. An electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction, insulating material
layer which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer is placed on a back
side of the electroluminescence light-emitting layer, whereby 40%
or more of a light emitted by the electroluminescence
light-emitting layer toward a back side enters the light-scatting,
high refraction, insulating material layer.
48. The electroluminescence device of claim 47, wherein an
insulating material layer is placed on a front side of the
electroluminescence light-emitting layer.
Description
FIELD OF INVENTION
[0001] The present invention relates to an electroluminescence
device (EL device) which emits a light by application of electric
energy.
BACKGROUND OF INVENTION
[0002] Recently, a liquid crystal display is widely employed as a
small-size, light-weight display. Since the liquid crystal per se
emits no light, a transmitted image is generally obtained utilizing
a back light supplied by a light source placed on a back side and
controlling the supplied light by a liquid crystal layer. A color
image can be obtained by placing a color filter on a surface of the
liquid crystal layer. A combination of colored lights transmitted
through the color filter gives a color image.
[0003] As is described above, the liquid crystal display requires a
light source and the energy consumption is high. Therefore, a small
size battery for supplying electric energy to the liquid crystal
display has been developed (for instance, lithium battery).
Nevertheless, there are limitations in the development of a
smaller-size and lighter-weight liquid crystal display. A
reflective liquid crystal display employing no back light has been
developed. In the use of the reflective liquid crystal display,
particularly, for obtaining a color image, a color image showing a
low contrast only can be obtained. Moreover, the image quality of
reflected image is largely varied depending on surrounding light
conditions. Therefore, the reflective liquid crystal display can be
utilized only in a specific field.
[0004] For these reasons, an electroluminescence device (generally
called "EL device") that per se emits a light by application of a
small amount of electric energy so that an image can be displayed
in the absence of a separately-provided light source has been given
an attention.
[0005] In the attached FIGS. 1 and 2, representative constitutions
of the conventional electroluminescence devices (EL devices) are
illustrated.
[0006] The EL device of FIG. 1 is an electroluminescence device
named a dispersion AC EL device comprising a transparent glass
substrate (or a transparent plastic material substrate, through
which a light emission is extracted) 11a, a transparent electrode
(ITO electrode) 12a, a light-emitting layer (generally having a
thickness of 50 to 100 .mu.m) 13, an insulating material layer 14b,
and a back electrode (aluminum electrode) 12b arranged in order. By
applying an alternative current between the transparent electrode
12a arranged on the front side (lower side in the figure) and the
back electrode 12b, a light is emitted in alternating electric
field. The emitted light is generally transmitted through the
transparent electrode 12a and the transparent substrate 11a, and
extracted on the front side. An ordinarily employed phosphor
particle is a particle of ZnS:Cu,Cl, ZnS:Cu,Al, or ZnS:Cu,Mn,Cl. It
is considered that an acicular Cu.sub.2S crystal deposits along a
lattice defect of ZnS particle (particle size: 5 to 30 .mu.m), and
it serves a site of electron source. Generally, on a surface of the
EL device is provided a protecting film. Moreover, various
auxiliary layers may be provided between these layers.
[0007] The EL device of FIG. 2 is an electroluminescence device
named a thin film AC EL device comprising a transparent glass
substrate (or a transparent plastic material substrate, through
which a light emission is extracted) 21a, a transparent electrode
(ITO electrode) 22a, a front insulating material layer
(light-transmitting insulating material layer having a thickness of
0.3 to 0.5 .mu.m, named first insulating material layer) 24a, a
light-emitting layer 23 made of a thin phosphor layer (generally
having a thickness 1 .mu.m or less) 23, a back insulating material
layer 24b, and a back electrode (aluminum electrode) 22b arranged
in order. By applying an alternative current between the
transparent electrode 22a arranged on a front side (lower side in
the figure) and the back electrode 22b, a light is emitted in the
light-emitting layer 23 under alternating electric field. The
emitted light is transmitted through the front insulating material
layer 24a, the transparent electrode 22a and the transparent
substrate 21a, and extracted on the front side. The light-emitting
layer of phosphor film is formed by various vapor depositing
methods or coating methods (utilizing a sol-gel method and others).
An auxiliary layer such as buffer layer may be placed between the
phosphor layer and the adjoining insulating material layers.
Generally, on a surface of the EL device is provided a protecting
film. Moreover, various auxiliary layers may be provided between
the above-mentioned layers.
[0008] General structures and component materials for the
conventional electroluminescence devices are described in detail in
"Electroluminescence Display" (written by INOKUTI Toshio, published
in 1991, by Sangyo Tosho Co., Ltd.).
[0009] Heretofore, a multi-colored image is formed on an
electroluminescence device on which a single electroluminescence
light-emitting layer is divided into two or more areas and plural
phosphors emitting different color lights are placed in these areas
separately. Recently, there has been proposed an
electroluminescence device having plural light-emitting composites
comprising light-emitting layers which emit different color lights
are placed one on another, whereby a multi-color image is
displayed. An example of the electroluminescence device for
displaying a multi-color image which comprises plural
light-emitting composites are illustrated in FIG. 26.
[0010] In FIG. 26, from a light-shielding back sheet (black sheet)
631 to a front protecting sheet (glass substrate) 632 (placed on a
light-extracting side, that is, a displaying side), an orange color
light-emitting layer 633, a green color light-emitting layer 634,
and a blue color light-emitting layer 635 are arranged. On both
sides of each light-emitting layer, an insulating layer and an
electrode layer are placed. In more detail, on both sides of the
orange color light-emitting layer 633, an insulating layer 731 and
electrodes 732a, 732b (the front electrode 732a is a transparent
electrode, and the back electrode 732b is an opaque aluminum
electrode) are placed. On both sides of the green color
light-emitting layer 634, an insulating layer 741 and electrodes
742a, 742b (both are transparent electrodes) are placed. On both
sides of the blue color light-emitting layer 635, an insulating
layer 751 and electrodes 752a, 752b (both are transparent
electrodes) are placed. Between the orange color light-emitting
composite and the green color light-emitting composite are placed
glass substrates 637 having a red filter 634 between them. Between
the green color light-emitting composite and the blue color
light-emitting composite is placed a transparent protecting film
638.
[0011] As is described above, it is considered that the
electroluminescence device (EL device) is an excellent display
device because of its self light-emitting property. However, there
are problems in the conventionally developed EL display products in
that the stability is poor and the amount of light emission is not
enough. It is known that the problem of stability is already solved
by various studies, but the problem of poor light emission should
be solved.
[0012] Particularly, the dispersion EL device has a problem in that
it shows a poor light emission efficiency and therefore an amount
of light emission taken outside is not enough. On the other hands,
a thin film EL device has a problem in that only an extremely small
amount of a light emission produced inside can be taken outside.
For solving these problems, various studies have been made. For
instance, there is a proposal to place a light-scattering film on
the glass substrate on the light-extraction side. However, the
effects of the known improvements are not enough.
[0013] Accordingly, the present invention has a main object to
provide an electroluminescence device from which an enough amount
of light emission can be taken outside, by applying an electric
power almost equivalent to that used for the conventional EL
devices.
[0014] Further, the invention has a main object to provide an
electroluminescence device showing a high light emission efficiency
and a high light emission-extracting efficiency, under an electric
power almost equivalent to that used for the conventional EL
devices.
DISCLOSURE OF INVENTION
[0015] As a result of studies on the problems of the conventional
electroluminescence devices, the inventor of the present invention
has discovered that a light emitted in the light-emitting layer can
be efficiently extracted on the outside by incorporating a
light-scattering layer having a high refractive index such as
almost the same as or higher than a refractive index of the
light-emitting layer on a front surface (from which a light is
extracted) and/or a back surface of the light-emitting layer and
further by adjusting a refractive index of material present in the
light-emitting layer and the light-scattering layer having a high
refractive index to a level similar to or higher than the
refractive index of the light-emitting layer. The present invention
is based on this discovery.
[0016] The inventor has further discovered that a light emitted in
a phosphor particle can be efficiently extracted on the outside by
imparting a light-scattering reflective property to a substrate on
the back side (back face sheet) and further imparting a
light-scattering reflective property to the dielectric material
layer which disperses and supports phosphor particles in the
light-emitting layer.
[0017] Furthermore, the inventor has discovered that a light
emitted in the phosphor particle can be efficiently extracted on
the outside by employing a complex particle which is prepared by
coating a phosphor particle with a coating material (e.g.,
dielectric material) which has a refractive index similar to or
higher than the refractive index of the phosphor particle, or by
employing a complex particle which is prepared by coating a
dielectric material particle with a phosphor layer and further with
a coating layer having a refractive index similar to or higher than
the refractive index of the coated phosphor layer.
[0018] From the first aspect, the present invention resides in a
dispersion electroluminescence device comprising a back face sheet,
a light-transmitting back electrode, a light-emitting layer
comprising electroluminescence light-emitting particles dispersed
in a dielectric material phase, a light-transmitting front
electrode, and a light-transmitting front protecting film arranged
in order, wherein the back face sheet shows a light-scattering
reflective property and the light-emitting layer shows a
light-scattering property.
[0019] From the second aspect, the invention resides in a
dispersion electroluminescence device comprising a back face sheet,
a back electrode, a light-emitting layer comprising
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the electroluminescence light-emitting particle comprises a
dielectric material particle coated with a phosphor layer which is
further coated with an outer coat layer.
[0020] From the third aspect, the invention resides in a dispersion
electroluminescence device comprising a back face sheet, a back
electrode, a light-scattering or non light-scattering,
light-emitting layer which comprises electroluminescence
light-emitting particles dispersed in a dielectric material phase,
a light-transmitting front electrode, and a light-transmitting
front protecting film arranged in order, wherein the
electroluminescence light-emitting particle comprises a dielectric
material particle coated with a phosphor layer.
[0021] From the fourth aspect, the invention resides in a
dispersion electroluminescence device comprising a back face sheet,
a light-transmitting back electrode, a light-emitting layer
comprising electroluminescence light-emitting particles dispersed
in a dielectric material phase, a light-transmitting front
electrode, and a light-transmitting front protecting film arranged
in order, wherein the back face sheet shows light reflection by a
light-scattering effect, a light-scattering, high refraction layer
which comprises as main component a material having a refractive
index of 80% or higher based on a refractive index of the
electroluminescence light-emitting layer is placed between the
light-transmitting front electrode and the front protecting film,
and a refractive index of material placed between the
light-emitting layer and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a front side enters
the light-scattering, high refraction layer.
[0022] From the fifth aspect, the invention resides in a dispersion
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer comprising electroluminescence light-emitting
particles dispersed in a dielectric material phase, a
light-transmitting front electrode, and a light-transmitting front
protecting film arranged in order, wherein the back face sheet is a
light-scattering reflective, high refraction sheet which comprises
as main component a material having a refractive index of 80% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and a refractive index of material placed
between the light-emitting layer and the back face sheet is
adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a back side enters
the back face sheet.
[0023] From the sixth aspect, the invention resides in a dispersion
electroluminescence device comprising a back face sheet, a back
electrode, a back insulating material layer, an electroluminescence
light-emitting layer comprising electroluminescence light-emitting
particles dispersed in a dielectric material phase, a
light-transmitting front electrode, a light-transmitting front
protecting film arranged in order, wherein the back insulating
material layer is a light-scattering, high refraction, insulating
material layer which comprises as main component a material having
a refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer, and 40% or more of a
light emitted by the electroluminescence light-emitting layer
toward a back side enters the back insulating layer.
[0024] From the seventh aspect, the invention resides in a
dispersion electroluminescence device comprising a back face sheet,
a light-transmitting back electrode, an electroluminescence
light-emitting layer comprising electroluminescence light-emitting
particles dispersed in a dielectric material phase, an front
insulating material layer, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the back face sheet shows light reflection by a
light-scattering effect, the front insulating material layer is a
light-scattering, high refraction, insulating material layer which
comprises as main component a material having a refractive index of
80% or higher, based on a refractive index of the
electroluminescence light-emitting layer, and 40% or more of a
light emitted by the electroluminescence light-emitting layer
toward a front side enters the front insulating material layer.
[0025] From the eighth aspect, the invention resides in a
dispersion electroluminescence device comprising a back face sheet,
a back electrode, a back insulating material layer, an
electroluminescence light-emitting layer comprising
electroluminescence light-emitting particles dispersed in a
dielectric material phase, a light-transmitting front electrode,
and a light-transmitting front protecting film arranged in order,
wherein the back insulating material layer has a thickness of 10
.mu.m or more and is a light-scattering, high refraction,
insulating material layer having a diffuse reflectance of 50% or
higher.
[0026] From the ninth aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a back
electrode, a back insulating material layer, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back insulating material layer has a thickness of 10 .mu.m or
more and is a light-scattering, high refraction, insulating
material layer having a diffuse reflectance of 50% or higher.
[0027] From the tenth aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet is a light-scattering reflective, high
refraction sheet comprising as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer, and a refractive
index of material placed between the light-emitting layer and the
back face sheet is adjusted, whereby 40% or more of a light emitted
by the electroluminescence light-emitting layer toward a back side
sheet enters the back face sheet.
[0028] From the eleventh aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, a back insulating material
layer, an electroluminescence light-emitting layer, a
light-transmitting front electrode, and a light-transmitting front
protecting film arranged in order, wherein the back face sheet
shows a light-scattering reflection, the back insulating material
layer is a light-scattering, high refraction, insulating material
layer which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer, and 40% or more of a
light emitted by the electroluminescence light-emitting layer
toward a back side enters the back insulating material layer.
[0029] From the twelfth aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction layer comprising as
main component a material having a refractive index of 80% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
[0030] From the thirteenth aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction, insulating material
layer comprising as main component a material having a refractive
index of 80% or higher based on a refractive index of the
electroluminescence light-emitting layer is placed on a front side
of the electroluminescence light-emitting layer, whereby 40% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction, insulating material layer.
[0031] From the fourteenth aspect, the invention resides in an
electroluminescence device comprising a back face sheet, a
light-transmitting back electrode, an electroluminescence
light-emitting layer, a light-transmitting front electrode, and a
light-transmitting front protecting film arranged in order, wherein
the back face sheet shows light reflection by a light-scattering
effect, a light-scattering, high refraction, insulating material
layer which comprises as main component a material having a
refractive index of 80% or higher based on a refractive index of
the electroluminescence light-emitting layer is placed on a back
side of the electroluminescence light-emitting layer, whereby 40%
or more of a light emitted by the electroluminescence
light-emitting layer toward a back side enters the light-scatting,
high refraction, insulating material layer.
BRIEF DESCRIPTION OF DRAWINGS
[0032] FIG. 1 is a schematic section indicating a constitution of
the conventional dispersion EL device.
[0033] FIG. 2 is a schematic section indicating a constitution of
the conventional thin film EL device.
[0034] Each of FIGS. 3 to 14 is a schematic section indicating a
constitution of the dispersion EL device according to the
invention.
[0035] Each of FIGS. 15 to 25 is a schematic section indicating a
constitution of the thin film EL device according to the
invention.
[0036] FIG. 26 is a schematic view indicating a constitution of the
conventional multi-color displaying EL device.
[0037] Each of FIG. 27 and FIG. 28 is a schematic section
indicating a constitution of the multi-color displaying dispersion
EL device according to the invention.
[0038] FIG. 29 is a schematic section indicating a constitution of
the multi-color displaying thin layer EL device according to the
invention.
[0039] FIG. 30 is a graph indicating a light-extraction efficiency
from a parallel plane.
PREFERRED EMBODIMENTS OF INVENTION
[0040] The preferred embodiments of the invention are described
below.
[0041] For the EL device of the first aspect of the invention, the
following embodiments are preferred.
[0042] (1) The electroluminescence particle is a phosphor particle
coated with an coating layer (e.g., a dielectric material
layer).
[0043] (2) The outer coating layer of the electroluminescence
light-emitting layer has a refractive index of 65% or higher based
on a refractive index of the phosphor particle of the
light-emitting layer.
[0044] (3) The outer coating layer of the electroluminescence
light-emitting layer has a refractive index of 75% or higher based
on a refractive index of the phosphor particle of the
light-emitting layer.
[0045] (4) The dielectric material layer of the light-emitting
layer has a refractive index of 65% or higher based on a refractive
index of the phosphor particle.
[0046] (5) The dielectric material layer of the light-emitting
layer has a refractive index of 75% or higher based on a refractive
index of the phosphor particle.
[0047] (6) The light-transmitting front electrode is a
light-transmitting electrode having a high refractive index.
[0048] (7) The particle size of the electroluminescence
light-emitting particle is in the range of 30 nm to 5 .mu.m.
[0049] (8) The dielectric material layer comprises inorganic or
organic fine particles dispersed in an organic polymer.
[0050] (9) A relationship between the radius of the
electroluminescence light-emitting particle and the thickness of
the coating layer of the particle is as follows:
(r-d)/r.ltoreq.(n.sub.2/n.sub.1).times.1.2
[0051] wherein r is a radius of the light-emitting particle, d is
the thickness of the coating layer, n.sub.2 is a refractive index
of the dielectric material layer of the light-emitting layer, and
n.sub.1 is a refractive index of the phosphor layer of the
light-emitting particle.
[0052] (10) The phosphor of the electroluminescence light-emitting
particle is a phosphor emitting a blue light, and there is placed a
phosphor layer (which converts the blue light into green light, red
light, or white light) between the light-transmitting front
electrode and the light-transmitting front protecting film.
[0053] (11) The phosphor of the electroluminescence light-emitting
particle is a phosphor emitting a ultraviolet light, and there is
placed a phosphor layer (which converts the ultraviolet light into
blue light, green light, red light, or white light) between the
light-transmitting front electrode and the light-transmitting front
protecting film.
[0054] (12) The phosphor layer placed between the
light-transmitting front electrode and the light-transmitting front
protecting film is a light-scattering phosphor layer.
[0055] (13) The phosphor of the electroluminescence light-emitting
particle is a phosphor emitting a blue light, a green light, an
orange light, or a red light.
[0056] (14) The phosphor of the electroluminescence light-emitting
particle is a phosphor emitting a white light.
[0057] (15) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting front protecting film.
[0058] For the EL device of the second aspect of the invention, the
following embodiments are preferred.
[0059] (1) The dielectric material layer comprises an organic
polymer, or comprises inorganic or organic fine particles dispersed
in an organic polymer.
[0060] (2) The light-emitting layer is a light-scattering
layer.
[0061] (3) The back electrode is a light-transmitting electrode,
and the back face sheet shows a light-scattering reflective
property.
[0062] (4) The outer dielectric material layer of the
electroluminescence light-emitting particle has a refractive index
of 65% or higher based on a refractive index of the phosphor layer
of the light-emitting particle.
[0063] (5) The outer dielectric material layer of the
electroluminescence light-emitting particle has a refractive index
of 75% or higher based on a refractive index of the phosphor layer
of the light-emitting particle.
[0064] (6) The dielectric material layer of the light-emitting
layer has a refractive index of 65% or higher based on a refractive
index of the phosphor layer of the light-emitting particle.
[0065] (7) The dielectric material layer of the light-emitting
layer has a refractive index of 75% or higher based on a refractive
index of the phosphor layer of the light-emitting particle. In this
case, the material of the dielectric material layer is not limited
to an organic polymer and can be an inorganic material or an
organic-inorganic complex material (including nano-composite
material).
[0066] (8) The back electrode is a light-transmitting electrode,
the back face sheet is a light-scattering, high refraction
reflective sheet which comprises as main component a material
having a refractive index of 80% or higher based on a refractive
index of the phosphor layer of the electroluminescence
light-emitting particle, and the refractive index of material
placed between the electroluminescence light-emitting particles and
the back face sheet is adjusted, whereby 40% or more of a light
emitted by the electroluminescence light-emitting particles toward
a back side enters the back face sheet.
[0067] (9) The back electrode is a light-transmitting electrode,
the back face sheet shows a light-scattering reflective property, a
light-scattering, high refraction layer comprising as main
component a material having a refractive index of 80% or higher
based on a refractive index of the phosphor layer of the
electroluminescence light-emitting particle is placed between the
front electrode and the front protecting film, and a refractive
index of material placed between the electroluminescence
light-emitting particles and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting particles toward a front side
enters the light-scattering, high refraction layer.
[0068] (10) The particle size of the electroluminescence
light-emitting particle is in the range of 30 nm to 5 .mu.m.
[0069] (11) A relationship between the radius of the
electroluminescence light-emitting particle and the thickness of
the coating layer of the particle is as follows:
(r-d)/r.ltoreq.(n.sub.2/n.sub.1).times.1.2
[0070] wherein r is a radius of the light-emitting particle, d is
the thickness of the coating layer, n.sub.2 is a refractive index
of the dielectric material layer of the light-emitting layer, and
n.sub.1 is a refractive index of the phosphor layer of the
light-emitting particle.
[0071] (12) The dielectric material particle inside of the
electroluminescence light-emitting particle has a dielectric
constant of three times or more the dielectric constant of the
phosphor layer of the light-emitting particle.
[0072] (13) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a blue light,
and there is placed a phosphor layer (which converts the blue light
into green light, red light, or white light) between the
light-transmitting front electrode and the light-transmitting front
protecting film.
[0073] (14) The phosphor layer of the electroluminescence
light-emitting particle comprises phosphor emitting a ultraviolet
light, and there is placed a phosphor layer (which converts the
ultraviolet light into blue light, green light, red light, or white
light) between the light-transmitting front electrode and the
light-transmitting front protecting film.
[0074] (15) The phosphor layer placed between the
light-transmitting front electrode and the light-transmitting front
protecting film is a light-scattering phosphor layer.
[0075] (16) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a blue light,
a green light, an orange light, or a red light.
[0076] (17) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a white
light.
[0077] For the EL device of the third aspect of the invention, the
following embodiments are preferred.
[0078] (1) The back electrode is a light-transmitting electrode,
and the back face sheet shows a light-scattering reflective
property.
[0079] (2) The dielectric material layer of the light-emitting
layer has a refractive index of 65% or higher based on a refractive
index of the phosphor layer of the light-emitting particle.
[0080] (3) The dielectric material particle inside of the
electroluminescence light-emitting particle has a dielectric
constant of three times or more the dielectric constant of the
phosphor layer of the light-emitting particle.
[0081] (4) The back electrode is a light-transmitting electrode,
the back face sheet is a light-scattering reflective, high
refraction sheet which comprises as main component a material
having a refractive index of 80% or higher based on a refractive
index of the phosphor layer of the electroluminescence
light-emitting particle, and the refractive index of material
placed between the light-emitting particles and the back face sheet
is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting particles toward a back side
enters the back face sheet.
[0082] (5) A refractive index of material placed between the
light-emitting particles and the back face sheet is adjusted,
whereby 70% or more of a light emitted by the electroluminescence
light-emitting particles toward a back side enters the back face
sheet.
[0083] (6) Any of materials placed between the electroluminescence
light-emitting particles and the back face sheet have a refractive
index of 80% or higher based on the refractive index of the
phosphor layer of the light-emitting particle.
[0084] (7) The back electrode is a light-transmitting electrode,
the back face sheet shows a light-scattering reflective property, a
light-scattering, high refraction layer comprising as main
component a material having a refractive index of 80% or higher
based on a refractive index of the phosphor layer of the
electroluminescence light-emitting particle is placed between the
front electrode and the front protecting film, and a refractive
index of material placed between the electroluminescence
light-emitting particles and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting particles toward a front side
enters the light-scattering, high refraction layer.
[0085] (8) A refractive index of material placed between the
electroluminescence light-emitting particles and the
light-scattering, high refraction layer is adjusted, whereby 70% or
more of a light emitted by the electroluminescence light-emitting
particles toward a front side enters the light-scattering, high
refraction layer.
[0086] (9) Any of layers and materials placed between the phosphor
layer of the electroluminescence light-emitting particles and the
light-scattering, high refraction layer have a refractive index of
80% or more based on the refractive index of the light-emitting
layer.
[0087] (10) Any of layers and materials placed between the phosphor
layer of the electroluminescence light-emitting particles and the
light-scattering, high refraction layer have a refractive index of
95% or more of the refractive index of the light-emitting
layer.
[0088] (11) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a blue light,
and there is placed a phosphor layer (which converts the blue light
into green light, red light, or white light) between the
light-transmitting front electrode and the light-transmitting front
protecting film.
[0089] (12) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a ultraviolet
light, and there is placed a phosphor layer (which converts the
ultraviolet light into blue light, green light, red light, or white
light) between the light-transmitting front electrode and the
light-transmitting front protecting film.
[0090] (13) The phosphor layer placed between the front
light-transmitting electrode and the light-transmitting front
protecting film is a light-scattering phosphor layer.
[0091] (14) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a blue light,
a green light, an orange light, or a red light.
[0092] (15) The phosphor layer of the electroluminescence
light-emitting particle comprises a phosphor emitting a white
light.
[0093] (16) The light-scattering, high refraction back face sheet
comprises a ceramic material.
[0094] (17) The light-scattering, high refraction back face sheet
is a composite of a glass sheet and a light-scattering, high
refraction layer.
[0095] (18) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting front protecting film.
[0096] For the EL device of the fourth aspect of the invention, the
following embodiments are preferred.
[0097] (1) An insulating material layer is placed between the
electroluminescence light-emitting layer and the light-transmitting
front electrode and/or the light-transmitting back electrode.
[0098] (2) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 95% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and a refractive index of material placed
between the light-emitting layer and the light-scattering, high
refraction layer is adjusted, whereby 70% or more of a light
emitted by the light-emitting layer toward a front side enters the
light-scattering, high refraction layer.
[0099] (3) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 99% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and a refractive index of material placed
between the light-emitting layer and the light-scattering, high
refraction layer is adjusted, whereby 85% or more of a light
emitted by the light-emitting layer toward a front side enters the
light-scattering, high refraction layer.
[0100] (4) The non light-transmitting back face sheet showing light
reflection by a light-scattering effect comprises a ceramic
material.
[0101] (5) The non light-transmitting back face sheet showing light
reflection by a light-scattering effect is a composite of a glass
sheet and a light-scattering high refraction layer.
[0102] (6) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0103] (7) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0104] (8) There are placed a color filter layer and/or an ND
filter layer between the light-scattering, high refraction layer
and the light-transmitting protecting film.
[0105] (9) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultraviolet light, and a phosphor layer which
absorbs the ultraviolet light and emits a visible light is placed
on the front side of the light-scattering, high refraction
layer.
[0106] (10) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and the light-scattering,
high refraction layer is a light-scattering, high refraction layer
which absorbs the ultra-violet light and emits a visible light.
[0107] (11) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and there is placed a phosphor
layer (which converts the blue light into green light, red light,
or white light) on the front side of the light-scattering, high
refraction layer.
[0108] (12) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and the light-scattering, high
refraction layer is a light-scattering, high refraction phosphor
layer which absorbs the blue light amd emits green light, red
light, or white light
[0109] For the EL devices of the fifth to seventh aspects of the
invention, the following embodiments are preferred.
[0110] (1) An insulating material layer is placed between the
electroluminescence light-emitting layer and the light-transmitting
front electrode and/or the light-transmitting back electrode.
[0111] (2) A light-scattering, high refraction layer which
comprises as main component a material having a refractive index of
80% or higher based on a refractive index of the
electroluminescence light-emitting layer is further placed between
the light-transmitting front electrode and the front protecting
film, and the refractive index of material placed between the
light-emitting layer and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a front side enters
the light-scattering, high refraction layer.
[0112] (3) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 95% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and the refractive index of material placed
between the light-emitting layer and the light-scattering, high
refraction layer is adjusted, whereby 70% or more of a light
emitted by the light-emitting layer toward a front side enters the
light-scattering, high refraction layer.
[0113] (4) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 99% or
higher, based on a refractive index of the electroluminescence
light-emitting layer, and the refractive index of material placed
between the light-emitting layer and the light-scattering, high
refraction layer is adjusted, whereby 85% or more of a light
emitted by the light-emitting layer toward a front side enters the
light-scattering, high refraction layer.
[0114] (5). The back face sheet is a light-scattering reflective,
high refraction sheet which comprises as main component a material
having a refractive index of 95% or higher based on a refractive
index of the electroluminescence light-emitting layer, and the
refractive index of material placed between the light-emitting
layer and the back face sheet is adjusted, whereby 70% or more of a
light emitted by the electroluminescence light-emitting particles
toward a back side enters the back face sheet.
[0115] (6) The back face sheet is a light-scattering reflective,
high refraction sheet which comprises as main component a material
having a refractive index of 99% or higher based on a refractive
index of the electroluminescence light-emitting layer, and the
refractive index of any material placed between the light-emitting
layer and the back face sheet is adjusted, whereby 85% or more of a
light emitted by the electroluminescence light-emitting particles
toward a back side enters the back face sheet.
[0116] (7) The back face sheet comprises ceramic material.
[0117] (8) The back face sheet is a composite of a glass sheet and
a light-scattering, high refraction layer.
[0118] (9) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0119] (10) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0120] (11) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting protecting film.
[0121] (12) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and a phosphor layer
absorbing the ultra-violet light and emitting a visible light is
placed on the back side of the light-transmitting protecting
film.
[0122] (13) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and a light-scattering
phosphor layer absorbing the ultra-violet light and emitting a
visible light is placed on the back side of the light-transmitting
protecting film.
[0123] (14) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a phosphor layer absorbing
the blue light and emitting a green light, a red light or a white
light is placed on the back side of the light-transmitting
protecting film.
[0124] (15) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a light-scattering phosphor
layer absorbing the blue light and emitting a green light, a red
light, or a white light is placed on the back side of the
light-transmitting protecting film.
[0125] (16) The electroluminescence light-emitting layer is a thin
film phosphor layer, or a phosphor particle-dispersed layer
comprising phosphor particles dispersed in a dielectric material
layer having a refractive index of 80% or higher based on the
refractive index of the phosphor particle.
[0126] For the EL device of the eighth aspect of the invention, the
following embodiments are preferred.
[0127] (1) The diffuse reflectance of the back insulating material
layer is 70% or higher.
[0128] (2) The diffuse reflectance of the back insulating material
layer is 90% or higher.
[0129] (3) The thickness of the back insulating material layer is
in the range of 10 to 100 .mu.m.
[0130] (4) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0131] (5) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0132] (6) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting protecting film.
[0133] (7) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultra-violet light, and a phosphor layer
absorbing the ultra-violet light and emitting a visible light is
placed on the back side of the light-transmitting protecting
film.
[0134] (8) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultra-violet light, and a light-scattering
phosphor layer absorbing the ultra-violet light and emitting a
visible light is placed on the back side of the light-transmitting
protecting film.
[0135] (9) The electroluminescence light-emitting layer comprises a
phosphor emitting a blue light, and a phosphor layer absorbing the
blue light and emitting a green light, a red light or a white light
is placed on the back side of the light-transmitting protecting
film.
[0136] (10) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a light-scattering phosphor
layer absorbing the blue light and emitting a green light, a red
light, or a white light is placed on the back side of the
light-transmitting protecting film.
[0137] For the EL device of the ninth aspect of the invention, the
following embodiments are preferred.
[0138] (1) The diffuse reflectance of the back insulating material
layer is 70% or higher.
[0139] (2) The diffuse reflectance of the back insulating material
layer is 90% or higher.
[0140] (3) The thickness of the back insulating material layer is
in the range of 10 to 100 .mu.m.
[0141] (4) The electroluminescence light-emitting layer is a thin
phosphor film.
[0142] (5) The electroluminescence light-emitting layer is a
light-emitting layer in which electroluminescence light-emitting
particles are dispersed in a dielectric material phase.
[0143] (6) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0144] (7) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0145] (8) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting protecting film.
[0146] (9) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultra-violet light, and a phosphor layer
absorbing the ultra-violet light and emitting a visible light is
placed on the back side of the light-transmitting protecting
film.
[0147] (10) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and a light-scattering
phosphor layer absorbing the ultra-violet light and emitting a
visible light is placed on the back side of the light-transmitting
protecting film.
[0148] (11) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a phosphor layer absorbing
the blue light and emitting a green light, a red light, or a white
light is placed on the back side of the light-transmitting
protecting film.
[0149] (12) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a light-scattering phosphor
layer absorbing the blue light and emitting a green light, a red
light, or a white light is placed on the back side of the
light-transmitting protecting film.
[0150] For the EL devices of the tenth and eleventh aspects of the
invention, the following embodiments are preferred.
[0151] (1) A light-scattering, high refraction layer which
comprises as main component a material having a refractive index of
80% or higher based on a refractive index of the
electroluminescence light-emitting layer is placed between the
light-transmitting front electrode and the front protecting film,
and a refractive index of material placed between the
light-emitting layer and the light-scattering, high refraction
layer is adjusted, whereby 40% or more of a light emitted by the
electroluminescence light-emitting layer toward a front side enters
the light-scattering, high refraction layer.
[0152] (2) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 95% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 70% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
[0153] (3) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 99% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 85% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
[0154] (4) The back face sheet is a light-scattering reflective,
high refraction sheet which comprises as main component a material
having a refractive index of 95% or higher based on a refractive
index of the electroluminescence light-emitting layer, and a
refractive index of material placed between the light-emitting
layer and the back face sheet is adjusted, whereby 70% or more of a
light emitted by the electroluminescence light-emitting particles
toward a back side enters the back face sheet.
[0155] (5) The back face sheet is a light-scattering reflective,
high refraction sheet which comprises as main component a material
having a refractive index of 99% or higher based on a refractive
index of the electroluminescence light-emitting layer, and a
refractive index of any material placed between the light-emitting
layer and the back face sheet is adjusted, whereby 85% or more of a
light emitted by the electroluminescence light-emitting particles
toward a back side enters the back face sheet.
[0156] (6) The back face sheet comprises ceramic material.
[0157] (7) The back face sheet is a composite of a glass sheet and
a light-scattering, high refraction layer.
[0158] (8) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0159] (9) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0160] (10) There are placed a color filter layer and/or an ND
filter layer between the light-transmitting front electrode and the
light-transmitting protecting film.
[0161] (11) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and a phosphor layer
absorbing the ultra-violet light and emitting a visible light is
placed on the back side of the light-transmitting protecting
film.
[0162] (12) The electroluminescence light-emitting layer comprises
a phosphor emitting a ultra-violet light, and a light-scattering
phosphor layer absorbing the ultra-violet light and emitting a
visible light is placed on the back side of the light-transmitting
protecting film.
[0163] (13) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a phosphor layer absorbing
the blue light and emitting a green light, a red light or a white
light is placed on the back side of the light-transmitting
protecting film.
[0164] (14) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a light-scattering phosphor
layer absorbing the blue light and emitting a green light, a red
light, or a white light is placed on the back side of the
light-transmitting protecting film.
[0165] (15) The electroluminescence light-emitting layer is a thin
phosphor layer, or a phosphor particle-dispersed layer comprising
phosphor particles dispersed in a dielectric material layer having
a refractive index of 80% or higher based on the refractive index
of the phosphor particle.
[0166] For the EL devices of the twelfth to fourteenth aspects of
the invention, the following embodiments are preferred.
[0167] (1) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 95% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the light-transmitting front
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 70% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
[0168] (2) The light-scattering, high refraction layer comprises as
main component a material having a refractive index of 99% or
higher based on a refractive index of the electroluminescence
light-emitting layer is placed between the front light-transmitting
electrode and the front protecting film, and a refractive index of
material placed between the light-emitting layer and the
light-scattering, high refraction layer is adjusted, whereby 85% or
more of a light emitted by the electroluminescence light-emitting
layer toward a front side enters the light-scattering, high
refraction layer.
[0169] (3) The opaque back face sheet showing light reflection by a
light-scattering effect comprises ceramic material.
[0170] (4) The opaque back face sheet showing light reflection by a
light-scattering effect is a composite of a glass sheet and a
light-scattering, high refraction layer.
[0171] (5) The electroluminescence light-emitting layer comprises a
phosphor emitting a visible light.
[0172] (6) The electroluminescence light-emitting layer comprises
two or more phosphor layers having different color hues from each
other which are placed in areas separated from each other.
[0173] (7) There are placed a color filter layer and/or an ND
filter layer between the light-scattering, high refraction layer
and the light-transmitting protecting film.
[0174] (8) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultra-violet light, and a phosphor layer
absorbing the ultra-violet light and emitting a visible light is
placed on the front side of the light-scattering, high refraction
layer.
[0175] (9) The electroluminescence light-emitting layer comprises a
phosphor emitting a ultra-violet light, and a light-scattering high
refraction phosphor layer is provided as the light-scattering, high
refraction layer.
[0176] (10) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a phosphor layer absorbing
the blue light and emitting a green light, a red light, or a white
light is placed on the front side of the light-scattering, high
refraction layer.
[0177] (11) The electroluminescence light-emitting layer comprises
a phosphor emitting a blue light, and a light-scattering high
refraction phosphor layer absorbing the blue light and emitting a
green light, a red light, or a white light is provided as the
light-scattering, high refraction layer.
[0178] The constitutions of the electroluminescence devices
according to the invention are described below in more detail, by
referring to the attached drawings which illustrate their
representative constitutions.
[0179] In the present specification, the term of high refraction
means that the refractive index is 80% or higher (preferably 95% or
higher, more preferably 99% or higher) based on the refractive
index of the dielectric material phase in the light-emitting layer.
The material or layer having the high refractive index means a
material or a layer is a material or a layer having such a high
refractive index.
[0180] FIG. 3 shows a representative constitution of the dispersion
EL device of the first aspect according to the invention. The EL
device comprises a back light-transmitting electrode 32b, a
light-emitting layer, a front light-transmitting electrode 32a, and
a light-transmitting protecting film 37 (or a wavelength-converting
phosphor layer, a color filter layer, or their combination) laid on
an opaque back face substrate 31b showing light-scattering
reflection. The light-emitting layer comprises phosphor particles
33 (particle size generally is in the range of 30 nm to 5 .mu.m,
preferably 50 nm to 2 .mu.m) dispersed in a dielectric material
phase 35, and shows a light-scattering property.
[0181] By applying an alternating voltage (several tens V to
several hundreds V, frequency 30 Hz to 10 KHz, the waveform is
optional but preferably is a sine wave) between the
light-transmitting electrode 32a arranged on the front side (lower
side in the figure) and the light-transmitting back electrode 32b,
the light-emitting layer emits a light under electric field. The
emitted light is extracted through the front protecting film 37.
There may be provided various auxiliary layers between the layers
of the EL device. Such modification can be applied to the EL
devices of the constitutions described below.
[0182] FIG. 4 shows an alternative representative constitution of
the dispersion EL device of the first aspect according to the
invention. The EL device comprises a light-transmitting back
electrode 32b, a light-emitting layer, a light-transmitting front
electrode 32a, and a light-transmitting protecting film 37 (or a
wavelength-converting phosphor layer, a color filter layer, or
their combination) laid on an opaque back face substrate 31b
showing light-scattering reflection. The light-emitting layer
comprises complex phosphor particles composed of phosphor particles
33 (particle size generally is in the range of 30 nm to 5 .mu.m,
preferably 50 nm to 2 .mu.m) coated with a coating layer 40 (layer
thickness generally is in the range of 100 nm to several tens
.mu.m) dispersed in a dielectric material phase 35 (preferably
comprising an inorganic material, or a complex material comprising
inorganic fine particles placed in an organic material), and shows
a light-scattering property.
[0183] FIG. 5 shows a representative constitution of the dispersion
EL device of the second aspect according to the invention. The EL
device comprises a light-transmitting back electrode 52b, a
light-emitting layer, a light-transmitting front electrode 52a, and
a light-transmitting protecting film 57 laid on a back
light-reflecting layer (or light reflecting substrate) 51b. The
light-emitting layer comprises complex phosphor particles composed
of dielectric material cores (in the spherical form or in different
form) 60b coated with a phosphor layer (thickness generally is in
the range of 30 nm to 50 .mu.m, preferably 50 nm to 2 .mu.m) which
is further coated with a coating layer 60a dispersed in a high
dielectric constant-organic polymer phase 55, and shows a
light-scattering property.
[0184] By applying an alternating current between the
light-transmitting electrode 52a arranged on the front side (lower
side in the figure) and the light-transmitting back electrode 52b,
the light-emitting layer emits a light under electric field. The
emitted light is extracted through the front protecting film
57.
[0185] The high dielectric constant-organic polymer employed in the
above-described constitution can be a high dielectric
constant-cyanoethylated cellulose resin (cyanoethylated cellulose,
cyanoethylated hydroxycellulose, cyanoethylated pullulan, etc.),
and may comprise high dielectric constant-super fine particles
(diameter: several nm to several .mu.m) of BaTiO.sub.3,
SrTiO.sub.3, TiO.sub.2, Y.sub.2O.sub.3 or the like dispersed in a
polymer (having not so high dielectric constant) such as styrene
resin, silicone resin, epoxy resin, or fluorinated vinylidene
resin.
[0186] FIG. 6 shows a representative constitution of the dispersion
EL device of the third aspect according to the invention. The EL
device comprises a light-transmitting back electrode 52b having a
high refractive index, a light-emitting layer, a light-transmitting
front electrode 52a, and a light-transmitting protecting film 57
(or a wavelength-converting phosphor layer, a color filter layer,
or their combination) laid on a light-reflective, high refraction
back layer (which may serve a substrate) 51b. The light-emitting
layer comprises complex phosphor particles composed of spherical
dielectric material core 60b coated with a phosphor layer 53 (layer
thickness generally is in the range of 30 nm to 5 .mu.m, preferably
50 nm to 2 .mu.m) dispersed in a high refraction, high dielectric
constant medium phase 60c (preferably comprising an inorganic
material, or a complex material comprising inorganic super-fine
particles placed in an organic material).
[0187] FIG. 7 shows a constitution of the dispersion EL device of
the fourth aspect according to the invention. The EL device of FIG.
7 comprises a light-transmitting back electrode (ITO, thickness:
0.01-20 .mu.m) 122b, a light-emitting layer comprising phosphor
particles dispersed and supported in a dielectric material phase
(thickness: 2-50 .mu.m, preferably 5-20 .mu.m, different phosphors
emitting lights of color hues of R, G and B are placed in divided
areas) 123, a light-transmitting front high refraction electrode
122a, a light-scattering, high refraction layer (thickness 1-50
.mu.m) 125, a color filter layer (R, G, B) 126, and a
light-transmitting protecting layer 127 are arranged in order on
(under, in FIG. 7) a high light-scattering reflective ceramic
substrate (opaque back face sheet) 121 placed on the back side
(side opposite to the side on which a light emitted in the device
is extracted). In the EL device of FIG. 7, the layers other than
the ceramic substrate 121 on the back side are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0188] The opaque back face sheet 121 can comprise a glass sheet
and an opaque layer laid on the glass sheet.
[0189] By applying an alternating voltage between the
light-transmitting electrode 122a arranged on the front side (lower
side in the figure) of the dispersion EL device of FIG. 7 and the
back electrode 112b, the light-emitting layer 123 emits a light
under electric field. The emitted light is extracted through the
front protecting film 127.
[0190] FIG. 8 shows another constitution of the dispersion EL
device of the fourth aspect according to the invention. The EL
device of FIG. 8 comprises a light-transmitting back electrode
(ITO, thickness: 0.01-20 .mu.m) 132b, a back insulating material
layer (thickness: 0.3-100 .mu.m) 134b, a light-emitting layer 133
comprising phosphor particles dispersed and supported in a
dielectric material phase, a light-transmitting front electrode
132a, a light-scattering, high refraction layer (thickness 0.3-20
.mu.m) 135, a color filter layer (R, G, B) 136, and a
light-transmitting protecting layer 137 are arranged in order on a
high light-scattering reflective ceramic substrate 131 placed on
the back side. In the EL device of FIG. 8, the layers other than
the ceramic substrate 131 on the back side are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0191] FIG. 9 shows a further constitution of the dispersion EL
device of the fourth aspect according to the invention. The EL
device of FIG. 9 comprises a light-transmitting back electrode
(ITO, thickness: 0.01-20 .mu.m) 142b, a light-emitting layer 143
comprising phosphor particles dispersed and supported in a
dielectric material phase, a light-scattering, high refraction,
insulating material layer (thickness: 1-50 .mu.m) 145, a
light-transmitting high refraction front electrode (thickness
0.01-20 .mu.m) 142a, a color filter layer (R, G, B) 146, and a
light-transmitting protecting layer 157 are arranged in order on a
high light-scattering reflective ceramic substrate 141 placed on
the back side. In the EL device of FIG. 9, the layers other than
the ceramic substrate 141 on the back side are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0192] FIG. 10 shows a constitution of the dispersion EL device of
the fifth aspect according to the invention. The EL device of FIG.
10 comprises a light-transmitting back electrode having a high
refractive index (ITO, thickness: 0.01-20 .mu.m) 222b, a
light-emitting layer comprising phosphor particles dispersed and
supported in a dielectric material phase (thickness: 2-50 .mu.m,
preferably 5-20 .mu.m, different phosphors emitting lights of color
hues of R, G and B are placed in divided areas) 223, a
light-transmitting front electrode 222a, a color filter layer (R,
G, B) 226, and a light-transmitting protecting layer 227 are
arranged in order on a high light-scattering reflective, high
refraction ceramic substrate (light-scattering reflective back face
sheet having a high refractive index) 221 placed on the back side
(side opposite to the side on which a light emitted in the device
is extracted). In the EL device of FIG. 10, the layers other than
the high refraction ceramic substrate 221 on the back side are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0193] The light-scattering reflective, high refraction back face
sheet 221 can comprise a glass sheet and a light-scattering, high
refraction layer laid on the glass sheet.
[0194] By applying an alternating voltage between the
light-transmitting electrode 222a arranged on the front side (lower
side in the figure) and the back electrode 212b, the light-emitting
layer 223 emits a light under electric field. The emitted light is
extracted through the front protecting film 227.
[0195] FIG. 11 shows a constitution of the dispersion EL device of
the sixth aspect according to the invention. The EL device of FIG.
11 comprises a light-transmitting, high refraction, back electrode
(ITO, thickness: 0.01-20 .mu.m) 232b, a high refraction, back
insulating material layer (thickness: 0.3-50 .mu.m) 234, a
light-emitting layer 233 comprising phosphor particles dispersed
and supported in a dielectric material phase, a light-transmitting
front electrode 232a, a color filter layer (R, G, B) 236, and a
light-transmitting protecting layer 237 are arranged in order on a
high light-scattering reflective, high refraction ceramic substrate
231 placed on the back side. In the EL device of FIG. 11, the
layers other than the high refraction ceramic substrate 231 on the
back side are essentially light-transmitting layers or opaque
layers capable of transmitting a certain amount of light.
[0196] FIG. 12 shows a constitution of the dispersion EL device of
the seventh aspect according to the invention. The EL device of
FIG. 12 comprises a light-transmitting, high refraction, back
electrode (ITO, thickness: 0.01-20 .mu.m) 242b, a light-emitting
layer 243 comprising phosphor particles dispersed and supported in
a dielectric material phase, a high refraction, front insulating
material layer (thickness: 0.3-1 .mu.m) 244a, a light-transmitting,
high refraction front electrode (thickness: 0.01-20 .mu.m) 242a, a
color filter layer (R, G, B) 246, and a light-transmitting
protecting layer 247 are arranged in order on a high
light-scattering reflective, high refraction ceramic substrate 241
placed on the back side. Also in the EL device of FIG. 12, the
layers other than the ceramic substrate 241 on the back side are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0197] FIG. 13 shows another constitution of the dispersion EL
device of the fifth aspect according to the invention. The EL
device of FIG. 13 comprises a light-transmitting, high refraction
back electrode (ITO, thickness: 0.01-20 .mu.m) 252b, a
light-emitting layer 253 comprising phosphor particles dispersed
and supported in a dielectric material phase, a light-transmitting
front electrode (thickness: 0.01-20 .mu.m) 252a, a
light-scattering, high refraction layer (thickness: 1-50 .mu.m)
255, a color filter layer (R, G, B) 256, and a light-transmitting
protecting layer 257 are arranged in order on a high
light-scattering reflective, high refraction ceramic substrate 251
placed on the back side. Also in the EL device of FIG. 13, the
layers other than the ceramic substrate 251 on the back side are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0198] FIG. 14 shows another constitution of the dispersion EL
device of the eighth aspect according to the invention. The EL
device of FIG. 14 comprises a back electrode (metal electrode or
non light-transmitting electrode) 342, a light-scattering
reflective, high refraction, insulating material layer having a
diffusion reflectance of 50% or more (thickness: 10-100 .mu.m) 343,
a light-emitting layer comprising phosphor particles dispersed and
supported in a dielectric material phase (thickness: 2-50 .mu.m,
preferably 5-20 .mu.m, different phosphors emitting lights of color
hues of R, G and B are placed in divided areas) 344, a
light-transmitting front electrode 346, a color filter layer (R, G,
B) 347, and a light-transmitting protecting layer 348 are arranged
in order on a transparent or opaque substrate 341 made of glass,
metal or ceramic placed on the back side (side opposite to the side
on which a light emitted in the device is extracted). In the EL
device of FIG. 14, the layers other than the back substrate 341,
the back electrode 342 and the light-scattering reflective, high
refraction, insulating material layer 343 on the back side are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0199] By applying an alternating voltage between the
light-transmitting electrode 346 arranged on the front side (lower
side in the figure) and the back electrode 342, the light-emitting
layer 344 emits a light under electric field. The emitted light is
extracted through the front protecting film 348.
[0200] FIG. 15 shows a constitution of the thin film EL device of
the ninth aspect according to the invention. The EL device of FIG.
15 comprises a back electrode (metal electrode or non
light-transmitting electrode) 332, a light-scattering reflective,
high refraction, insulating material layer having a diffusion
reflectance of 50% or more (thickness: 10-100 .mu.m) 333, a
light-emitting layer comprising a thin phosphor film (thickness:
0.1-3 .mu.m, different phosphors emitting lights of color hues of
R, G and B are placed in divided areas) 334, a front insulating
material layer (thickness: 0.3-1 .mu.m) 335, a light-transmitting
front electrode 336, a color filter layer (R, G, B) 337, and a
light-transmitting protecting layer 338 are arranged in order on a
transparent or opaque substrate 331 made of glass, metal or ceramic
placed on the back side (side opposite to the side on which a light
emitted in the device is extracted). In the EL device of FIG. 15,
the layers other than the back face substrate 331, the back
electrode 332 and the light-scattering reflective, high refraction,
insulating material layer 333 on the back side are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0201] By applying an alternating voltage between the
light-transmitting electrode 336 arranged on the front side (lower
side in the figure) and the back electrode 332, the light-emitting
layer 334 emits a light under electric field. The emitted light is
extracted through the front protecting film 338.
[0202] In the case that the light-emitting layer 334 is a thin film
phosphor layer, it can be prepared utilizing various deposition
methods or coating methods (such as sol-gel method). Auxiliary
layers such as a buffer layer may be provided between the
light-emitting layer 334 and the front and/or back insulating
material layers 333, 335.
[0203] FIG. 16 shows a constitution of the thin film EL devices of
the tenth and eleventh aspects according to the invention. The EL
device of FIG. 16 comprises a light-transmitting, high refraction
back electrode (ITO, thickness: 0.01-20 .mu.m) 432, a high
refraction, back insulating material layer (thickness: 0.3-50
.mu.m) 434b, a light-emitting layer comprising a thin phosphor film
(thickness: 0.1-3 .mu.m, different phosphors emitting lights of
color hues of R, G and B are placed in divided areas) 433, a front
insulating material layer (thickness: 0.3-1 .mu.m) 434a, a
light-transmitting front electrode 432a, a color filter layer (R,
G, B) 436, and a light-transmitting protecting layer 437 are
arranged in order on a high refraction ceramic substrate 431b
showing a high light-scattering reflection placed on the back side
(side opposite to the side on which a light emitted in the device
is extracted). In the EL device of FIG. 16, the layers other than
the high refraction, back ceramic substrate 431b are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0204] By applying an alternating voltage between the
light-transmitting electrode 432a arranged on the front side (lower
side in the figure) and the back electrode 432b, the light-emitting
layer 433 emits a light under electric field. The emitted light is
extracted through the front protecting film 437.
[0205] The light-emitting thin film layer 433 can be prepared
utilizing various deposition methods or coating methods (such as
sol-gel method). Auxiliary layers such as a buffer layer may be
provided between the light-emitting layer 433 and the front and/or
back insulating material layers 434a, 434b.
[0206] FIG. 17 shows another constitution of the thin film EL
devices of the tenth and eleventh aspects according to the
invention. The EL device of FIG. 17 comprises a light-transmitting,
high refraction back electrode (ITO, thickness: 0.01-20 .mu.m)
442b, a high refraction, back insulating material layer (thickness:
0.3-50 .mu.m) 444b, a light-emitting layer comprising a thin
phosphor film (thickness: 0.1-3 .mu.m, different phosphors emitting
lights of color hues of R, G and B are placed in divided areas)
443, a light-scattering reflective, front insulating material layer
(thickness: 0.3-20 .mu.m) 444a, a light-transmitting front
electrode (thickness: 0.01-20 .mu.m) 442a, a front phosphor layer
(thickness: 5-20 .mu.m, W (non-emitting), or G (green
light-emitting), or R (red light-emitting)) 448a, a color filter
layer (R, G, B) 446, and a light-transmitting protecting layer 447
are arranged in order on a high refraction ceramic substrate 441b
showing a high light-scattering reflection placed on the back side.
Also in the EL device of FIG. 17, the layers other than the high
refraction, back ceramic substrate 441b are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0207] FIG. 18 shows a further constitution of the thin film EL
devices of the tenth and eleventh aspects according to the
invention. The EL device of FIG. 18 comprises a light-transmitting,
high refraction back electrode (ITO, thickness: 0.01-20 .mu.m)
452b, a high refraction, back insulating material layer (thickness:
0.3-50 .mu.m) 454b, a light-emitting layer comprising a thin
phosphor film (thickness: 0.1-3 .mu.m, different phosphors emitting
lights of color hues of R, G and B are placed in divided areas)
453, a light-scattering, high refraction, front insulating material
layer (thickness: 0.3-1 .mu.m) 454a, a light-transmitting, high
refraction front electrode (thickness: 0.01-20 .mu.m) 452a, a front
phosphor layer (thickness: 5-20 .mu.m, W (non-emitting), or G
(green light-emitting), or R (red light-emitting)) 458a, and a
light-transmitting protecting layer 457 are arranged in order on a
high refraction ceramic substrate 451b showing a high
light-scattering reflection placed on the back side. Also in the EL
device of FIG. 18, the layers other than the high refraction, back
ceramic substrate 451b are essentially light-transmitting layers or
opaque layers capable of transmitting a certain amount of
light.
[0208] FIG. 19 shows a still further constitution of the thin film
EL devices of the tenth and eleventh aspects according to the
invention. The EL device of FIG. 19 comprises a light-transmitting,
high refraction back electrode (ITO, thickness: 0.01-20 .mu.m)
462b, a high refraction, back insulating material layer (thickness:
0.3-100 .mu.m) 464b, a light-emitting layer comprising a thin
phosphor film (thickness: 0.1-3 .mu.m, different phosphors emitting
lights of color hues of R, G and B are placed in divided areas)
463, a light-scattering, high refraction, front insulating material
layer (thickness: 0.3-20 .mu.m) 464a, a light-transmitting front
electrode (thickness: 0.01-20 .mu.m) 462a, a color filter layer (R,
G, B) 466, and a light-transmitting protecting layer 467 are
arranged in order on a high refraction ceramic substrate 461b
showing a high light-scattering reflection placed on the back side.
Also in the EL device of FIG. 19, the layers other than the back
ceramic substrate 461b are essentially light-transmitting layers or
opaque layers capable of transmitting a certain amount of
light.
[0209] FIG. 20 shows a still further constitution of the thin film
EL devices of the tenth and eleventh aspects according to the
invention. The EL device of FIG. 20 comprises a light-transmitting,
high refraction back electrode (ITO, thickness: 0.01-20 .mu.m)
472b, a high refraction, back insulating material layer (thickness:
0.3-100 .mu.m) 474b, a light-emitting layer comprising a thin
phosphor film (thickness: 0.1-3 .mu.m, different phosphors emitting
lights of color hues of R, G and B are placed in divided areas)
473, a light-scattering reflective, high refraction, front
insulating material layer (also serving as a light-scattering
layer, thickness: 0.3-20 .mu.m) 474a or 475a, a light-transmitting
front electrode 472a, a color filter layer (R, G, B) 476, and a
light-transmitting protecting layer 477 are arranged in order on a
light-scattering reflective, high refraction substrate composed of
a glass substrate 471a on the back side and a light-scattering,
high refraction layer (thickness: 10-100 .mu.m) 479 or 475b placed
on the back side. Also in the EL device of FIG. 20, the layers
other than the back light-scattering reflective, high refraction
substrate 479 are essentially light-transmitting layers or opaque
layers capable of transmitting a certain amount of light.
[0210] FIG. 21 shows a still further constitution of the thin film
EL devices of the tenth and eleventh aspects according to the
invention. The EL device of FIG. 21 comprises a light-transmitting
back electrode (ITO, thickness: 0.01-20 .mu.m) or a metal electrode
482b, a high refraction, back insulating material layer (also
serving as a light-scattering layer, thickness: 0.3-100 .mu.m) 484b
(485b), a light-emitting layer comprising a thin phosphor film
(thickness: 0.1-3 .mu.m, which comprises a UV light-emitting
phosphor) 483, a front insulating material layer (thickness: 0.3-1
.mu.m) 484a, a light-transmitting front electrode (thickness:
0.01-20 .mu.m) 482a, a color filter layer (R, G, B) 486, and a
light-transmitting protecting layer 487 are arranged in order on a
high light-scattering reflective, high refraction ceramic substrate
or a glass substrate 481b on the back side. Also in the EL device
of FIG. 21, the layers other than the high refraction back ceramic
substrate 481b are essentially light-transmitting layers or opaque
layers capable of transmitting a certain amount of light.
[0211] FIG. 22 shows a constitution of the thin film EL devices of
the twelfth to fourteenth aspects according to the invention. The
EL device of FIG. 22 comprises a light-transmitting back electrode
(ITO, thickness: 0.01-20 .mu.m) 532b, a back insulating material
layer (thickness: 0.3-100 .mu.m) 534b, a light-emitting layer
comprising a thin phosphor film (thickness: 0.1-3 .mu.m, different
phosphors emitting lights of color hues of R, G and B are placed in
divided areas) 533, a high refraction, front insulating material
layer (thickness: 0.3-1 .mu.m) 534a, a light-transmitting, high
refraction front electrode 532a, a light-scattering, high fraction
layer (thickness: 1-50 .mu.m) 535a, a color filter layer (R, G, B)
536, and a light-transmitting protecting layer 537 are arranged in
order on a ceramic substrate 531b showing a high light-scattering
reflection placed on the back side (side opposite to the side on
which a light emitted in the device is extracted). In the EL device
of FIG. 22, the layers other than the back ceramic substrate 531b
are essentially light-transmitting layers or opaque layers capable
of transmitting a certain amount of light.
[0212] By applying an alternating voltage between the
light-transmitting electrode 532a arranged on the front side (lower
side in the figure) and the back electrode 532b, the light-emitting
layer 533 emits a light under electric field. The emitted light is
extracted through the front protecting film 537.
[0213] The light-emitting thin film layer 533 can be prepared
utilizing various deposition methods or coating methods (such as
sol-gel method). Auxiliary layers such, as a buffer layer may be
provided between the light-emitting layer 533 and the front and/or
back insulating material layers 534a, 534b.
[0214] FIG. 23 shows another constitution of the thin film EL
devices of the twelfth to fourteenth aspects according to the
invention. The EL device of FIG. 23 comprises a light-transmitting
back electrode (ITO, thickness: 0.01-20 .mu.m) 542b, a back
insulating material layer (thickness: 0.3-100 .mu.m) 544b, a
light-emitting layer comprising a thin phosphor film (thickness:
0.1-3 .mu.m, different phosphors emitting lights of color hues of
R, G and B are placed in divided areas) 543, a high refraction,
front insulating material layer (thickness: 0.3-1 .mu.m) 544a, a
light-transmitting front electrode 542a, a light-scattering, high
fraction layer (thickness: 1-50 .mu.m) 545a, a front phosphor layer
(thickness: 5-20 .mu.m, W (non-emitting), or G (green
light-emitting), or R (red light-emitting)) 548a, and a
light-transmitting protecting layer 547 are arranged in order on a
ceramic substrate 541b showing a high light-scattering reflection
placed on the back side. Also in the EL device of FIG. 23, the
layers other than the back ceramic substrate 541b are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0215] FIG. 24 shows a further constitution of the thin film EL
devices of the twelfth to fourteenth aspects according to the
invention. The EL device of FIG. 24 comprises a light-transmitting
back electrode (ITO, thickness: 0.01-20 .mu.m) 552b, a back
insulating material layer (thickness: 0.3-50 .mu.m) 554b, a
light-emitting layer comprising a thin phosphor film (thickness:
0.1-3 .mu.m, comprising a UV light-emitting phosphor) 553, a high
refraction, front insulating material layer (thickness: 0.3-20
.mu.m, also serving as a light-scattering layer) 554a or 555a, a
light-transmitting, high refraction front electrode (thickness:
0.01-20 .mu.m) 552a, a color filter layer (R, G, B) 556, and a
light-transmitting protecting layer 557 are arranged in order on a
ceramic substrate 551b showing a high light-scattering reflection
placed on the back side. Also in the EL device of FIG. 24, the
layers other than the back ceramic substrate 551b are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0216] FIG. 25 shows a still further constitution of the thin film
EL devices of the twelfth to fourteenth aspects according to the
invention. The EL device of FIG. 25 comprises a light-transmitting
back electrode (ITO, thickness: 0.01-20 .mu.m) 562b, a back
insulating material layer (thickness: 0.3-50 .mu.m) 564b, a
light-emitting layer comprising a thin phosphor film (thickness:
0.1-3 .mu.m, different phosphors emitting lights of color hues of
R, G and B are placed in divided areas) 563, a high refraction,
front insulating material layer (thickness: 0.3-20 .mu.m, also
serving as a light-scattering layer) 564a or 565a, a
light-transmitting front electrode 562a, a color filter layer (R,
G, B) 566, and a light-transmitting protecting layer 567 are
arranged in order on a light-scattering reflective substrate
composed of a glass substrate 561a on the back side and a
light-scattering reflective layer (thickness: 10-150 .mu.m) placed
on the back side. Also in the EL device of FIG. 25, the layers
other than the back light-scattering reflective layer 569 are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0217] FIG. 27 shows a constitution of a multi-color
image-displaying dispersion EL device having a composite of plural
light-emitting layers according to the invention. This EL device
comprises a light-transmitting back electrode (ITO, thickness:
0.01-20 .mu.m) 642a, a first light-emitting layer comprising
phosphor particles dispersed and supported in a dielectric material
phase (thickness: 2-50 .mu.m, preferably 5-20 .mu.m, a phosphor
emitting a light of a color hue of R, G, or B is uniformly placed)
643, a high refraction, light-transmitting electrode 642b, a second
light-emitting layer comprising phosphor particles dispersed and
supported in a dielectric material phase (thickness: 2-50 .mu.m,
preferably 5-20 .mu.m, a phosphor emitting a light of a color hue
which differs from the color hue of the phosphor placed in the
first light-emitting layer is uniformly placed) 644, a high
refraction, front light-transmitting electrode 642c, an insulating
material layer (thickness: 0.3-100 .mu.m) 645, a high refraction,
back light-transmitting electrode 642d, a third light-emitting
layer comprising phosphor particles dispersed and supported in a
dielectric material phase (thickness: 2-50 .mu.m, preferably 5-20
.mu.m, a phosphor emitting a light of a color hue which differs
from the color hues of the phosphors placed in the first and second
light-emitting layers are uniformly placed) 646, a high refraction,
front light-transmitting electrode 642e, a light-scattering, high
refraction layer (thickness: 1-50 .mu.m) 647, and a
light-transmitting protecting layer 648 are arranged in order on a
ceramic substrate (opaque back face sheet) 641 showing a high
light-scattering reflection placed on the back side (side opposite
to the side on which a light emitted in the device is extracted).
In the EL device of FIG. 27, the layers other than the back ceramic
substrate 641 are essentially light-transmitting layers or opaque
layers capable of transmitting a certain amount of light.
[0218] In the dispersion EL device of FIG. 27, the light-emitting
layer 643 emits a light under electric field, by applying an
alternating voltage between the light-transmitting electrode 642a
and the light-transmitting electrode 642b. In the same way, the
light-emitting layer 644 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 642b and the light-transmitting electrode 642c, and the
light-emitting layer 646 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 642d and the light-transmitting electrode 642e. By
applying the alternating voltage in an optional way, the desired
light-emission is taken from the front protecting film 648 through
the light-scattering, high refraction layer 647.
[0219] There may be provided an insulating material layer between
each light-emitting layer (phosphor layer) and the
light-transmitting electrode. The EL device can have various
auxiliary layers such as a buffer layer between the provided
layers. These variations can be adopted in the various EL devices
described below.
[0220] The opaque back face sheet 641 can be composed of a glass
sheet and an opaque layer provided on the glass sheet.
[0221] FIG. 28 shows another constitution of a multi-color
image-displaying dispersion EL device having a composite of plural
light-emitting layers according to the invention. This EL device
comprises a light-transmitting back electrode (ITO, thickness:
0.01-20 .mu.m) 652a, a first light-emitting layer comprising
phosphor particles dispersed and supported in a dielectric material
phase (thickness: 2-50 .mu.m, preferably 5-20 .mu.m, a phosphor
emitting a light of a color hue of R, G, or B is uniformly placed)
653, a light-transmitting, high refraction electrode 652b, a second
light-emitting layer comprising phosphor particles dispersed and
supported in a dielectric material phase (thickness: 2-50 .mu.m,
preferably 5-20 .mu.m, a phosphor emitting a light of a color hue
which differs from the color hue of the phosphor placed in the
first light-emitting layer is uniformly placed) 654, a
light-transmitting, high refraction electrode 652c, an insulating
material layer (thickness: 0.3-100 .mu.m) 655, a
light-transmitting, high refraction back electrode 652d, a third
light-emitting layer comprising phosphor particles dispersed and
supported in a dielectric material phase (thickness: 2-50 .mu.m,
preferably 5-20 .mu.m, a phosphor emitting a light of a color hue
which differs from the color hues of the phosphors placed in the
first and second light-emitting layers is uniformly placed) 656, a
light-transmitting, high refraction front electrode 652e, and a
light-transmitting protecting layer 658 are arranged in order on a
high refraction ceramic substrate (light-scattering reflective,
high refraction sheet) 651 showing a high light-scattering
reflection placed on the back side (under the back side in FIG.
28). Also in the EL device of FIG. 28, the layers other than the
high refraction, back ceramic substrate 651 are essentially
light-transmitting layers or opaque layers capable of transmitting
a certain amount of light.
[0222] In the dispersion EL device of FIG. 28, the light-emitting
layer 653 emits a light under electric field, by applying an
alternating voltage between the light-transmitting electrode 652a
and the light-transmitting electrode 652b. In the same way, the
light-emitting layer 654 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 652b and the light-transmitting electrode 652c, and the
light-emitting layer 656 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 652d and the light-transmitting electrode 652e. By
applying the alternating voltage in an optional way, the desired
light-emission is taken from the front protecting film 658. The
light emitted toward the back side by each light-emitting layer is
reflected with scattering by the light refraction back ceramic
substrate 651 and a portion of the reflected light is taken from
the front protecting film 658.
[0223] The light-scattering reflective, high refraction sheet 651
can be composed of a glass sheet and a light-scattering, high
refraction layer having a high light-scattering reflection provided
on the glass sheet.
[0224] FIG. 29 shows a constitution of a multi-color
image-displaying thin film EL device according to the invention.
This EL device comprises a light-transmitting back electrode (ITO,
thickness: 0.01-20 .mu.m) 662a, an insulating material layer
(thickness: 0.3-100 .mu.m, the same hereinbelow) 665a, a first
light-emitting layer comprising a phosphor film (thickness: 0.1-3
.mu.m, made of a phosphor film emitting a light of hue of R, G, or
B) 663, an insulating material layer 665b, a light-transmitting,
high refraction electrode 662b, an insulating material layer 665c,
a second light-emitting layer (made of a phosphor film emitting a
light of hue of R, G, or B which differs from the hue of light of
the first light-emitting layer) 664, an insulating material layer
665d, a light-transmitting, high refraction front electrode 662c,
an insulating material layer (thickness: 0.3-100 .mu.m) 665, a
light-transmitting, high refraction back electrode 652d, a third
light-emitting layer (made of a phosphor film emitting a light of
hue of R, G, or B which differs from the hues of lights of the
first and second light-emitting layers) 666, an insulating material
layer 665g, a light-transmitting, high refraction front electrode
662e, a light-scattering, high refraction layer (thickness: 1-50
.mu.m) 667, and a light-transmitting protecting layer 668 are
arranged in order on a ceramic substrate (opaque back face sheet)
661 showing a high light-scattering reflection placed on (under, in
FIG. 29) the back side (side opposite to the side on which a light
emitted in the device is extracted). In the EL device of FIG. 29,
the layers other than the back ceramic substrate 661 are
essentially light-transmitting layers or opaque layers capable of
transmitting a certain amount of light.
[0225] In the thin film EL device of FIG. 29, the light-emitting
layer 663 emits a light under electric field, by applying an
alternating voltage between the light-transmitting electrode 662a
and the light-transmitting electrode 662b. In the same way, the
light-emitting layer 664 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 662b and the light-transmitting electrode 662c, and the
light-emitting layer 666 emits a light under electric field, by
applying an alternating voltage between the light-transmitting
electrode 662d and the light-transmitting electrode 662e. By
applying the alternating voltage in an optional way, the desired
light-emission is taken from the front protecting film 668 through
the light-scattering, high refraction layer 667.
[0226] FIG. 30 is a graph indicating a light extraction efficiency
from parallel planes which explains the enhancement of a emission
efficiency in the electroluminescence device of the invention. In
more detail, a relationship between a refractive index ratio
(n.sub.1/n.sub.2) and the extraction efficiency .eta. in the case
that a light is extracted in a layer having a refractive index
n.sub.2 from a light-emitting layer having a refractive index
n.sub.1 is expressed by the graph of FIG. 30. The extraction
efficiency .eta. decreases by 30%, 42%, and 55% in the case that
the difference of refractive index is 5%, 10%, and 20%,
respectively. The graph indicates the case, in consideration of a
single surface of the light-emitting layer. In the case that a
light advances both sides of the light-emitting layer and the light
advancing on one side only is extracted, the extraction efficiency
decreases to a half, unless no reflection on the opposite side is
considered.
[0227] Materials and sizes of the substrate and various layers
constituting the electroluminescence device of the invention are
described below.
[0228] [Opaque Substrate Showing Light-Scattering Reflection]
[0229] Representative examples of the opaque substrates showing
light-scattering reflection are ceramic substrates. Examples of
materials of the ceramic substrates include Y.sub.2O.sub.3,
Ta.sub.2O.sub.5, BaTa.sub.2O.sub.6, BaTiO.sub.3, TiO.sub.2,
Sr(Zr,Ti)O.sub.3, SrTiO.sub.3, PbTiO.sub.3, Al.sub.2O.sub.3,
Si.sub.3N.sub.4, ZnS, ZrO.sub.2, PbNbO.sub.3, and Pb(Zr,Ti)O.sub.3.
Alternatively, a transparent substrate such as glass sheet or a
metal substrate coated with a light-scattering reflective layer can
be employed. The light-scattering reflective layer can be prepared
from the materials of the below-mentioned insulating material layer
and the matrix components of the below-mentioned phosphors,
provided that the materials and components have essentially no
light absorption in the utilized wavelength region. The structure
is prepared by forming areas (voids or particles having submicron
level to several micron level) having different refractive indexes
in the interior of the layer. The ceramic substrate can be prepared
by heating a screen-printed material to form a sintered
material.
[0230] [Glass Substrate]
[0231] The representative examples are non-alkaline glass sheets
(sheets of barium borosilicate glass and aluminosilicate
glass).
[0232] [Light-Scattering Reflective Layer]
[0233] The light-scattering reflective layer can be prepared from
the materials of the below-mentioned insulating material layer and
the matrix components of the below-mentioned phosphors, provided
that the materials and components have essentially no light
absorption in the utilized wavelength. The structure is prepared by
forming areas (voids or particles having submicron level to several
micron level) having different refractive indexes in the interior
of the layer.
[0234] [Light-Transmitting Electrode]
[0235] There are mentioned ITO, ZnO:Al, complex oxides (described
in JP-A-10-190028), GaN materials (described in JP-A-6-150723),
Zn.sub.2In.sub.2O.sub.5,
(Zn,Cd,Mg)O--(B,Al,Ga,In,Y).sub.2O.sub.3--(Si,Ge-
,Sn,Pb,Ti,Zr)O.sub.2,
(Zn,Cd,Mg)O--(B,Al,Ba,In,Y).sub.2O.sub.3--(Si,Sn,Pb)- O, material
comprising MgO--In.sub.2O.sub.3, and SnO.sub.2 materials (described
in JP-A-8-262225, JP-A-8-264022, and JP-A-8-264023).
[0236] [Phosphors in the Light-Emitting Layer]
[0237] UV (UV light-emitting phosphor): ZnF.sub.2:Gd
[0238] B (blue light-emitting phosphor): BaAl.sub.2S.sub.4:Eu,
CaS:Pb, SrS:Ce, SrS:Cu, CaGa.sub.2S.sub.4:Ce
[0239] G (green light-emitting phosphor): (Zn,Mg)S:Mn, ZnS:Tb,F,
Ga.sub.2O.sub.3:Mn
[0240] R (red light-emitting phosphor): (Zn,Mg)S:Mn, CaS:Eu,
ZnS:Sm,F, Ga.sub.2O.sub.3:Cr
[0241] [Material for Coating Phosphor Particle]
[0242] There can be mentioned Y.sub.2O.sub.3, Ta.sub.2O.sub.5,
BaTa.sub.2O.sub.6, BaTiO.sub.3, TiO.sub.2, Sr(Zr,Ti)O.sub.3,
SrTiO.sub.3, PbTiO.sub.3, Al.sub.2O.sub.3, Si.sub.3N.sub.4, ZnS,
ZrO.sub.2, PbNbO.sub.3, and Pb(Zr,Ti)O.sub.3. It is preferred that
the material has a high dielectric constant and high resistance to
dielectric breakdown, and forms an interfacial level on the
phosphor particle surface to serve as an electron-supplying source.
The material can be light-scattering material such as a sintered
material, provided that the layer does not prominently decrease the
dielectric constant of the layer.
[0243] [Material for Insulating Material Layer and Insulating
Material Phase of Light-Emitting Layer]
[0244] (1) A high dielectric constant organic polymer such as high
dielectric constant cyanoethylated cellulose (e.g., cyanoethylated
cellulose, cyanoethylated hydroxycellulose, and cyanoethylatated
pullulan), or a dispersion of high electric constant fine particles
(diameter: several nm to several .mu.m) such as particles of
BaTiO.sub.3, SrTiO.sub.3, TiO.sub.2 or Y.sub.2O.sub.3 dispersed in
a an organic polymer having a relatively low dielectric constant,
such as styrene resin, silicone resin, epoxy resin, or fluorinated
vinylidene resin.
[0245] (2) Y.sub.2O.sub.3, Ta.sub.2O.sub.5, BaTa.sub.2O.sub.6,
BaTiO.sub.3, TiO.sub.2, Sr(Zr,Ti)O.sub.3, SrTiO.sub.3, PbTiO.sub.3,
Al.sub.2O.sub.3, Si.sub.3N.sub.4, ZnS, ZrO.sub.2, PbNbO.sub.3, and
Pb(Zr,Ti)O.sub.3. It is preferred that the material has a high
dielectric constant and high resistance to dielectric breakdown.
The light-scattering property can be given by employing a material
which has a refractive index differing from the refractive index of
the phosphor particle (or the dielectric material-coated phosphor
particle), or forming areas (voids or particles having submicron
level to several micron level) having different refractive indexes
in the interior of the layer.
[0246] [Light-Transmitting, High Refraction Electrode]
[0247] The materials described above as the material for the
light-transmitting electrode can be employed under the condition
that the materials have a refractive index equivalent to or higher
than the refractive index of the dielectric material phase in the
light-emitting layer.
[0248] [Light-Scattering, High Refraction Layer]
[0249] The materials described above as the material for the
light-scattering reflective layer can be employed under the
condition that the materials have a refractive index equivalent to
or higher than the refractive indexes of the light-emitting layer
and intermediate layer(s).
[0250] [Insulating Material Layer]
[0251] There can be mentioned Y.sub.2O.sub.3, Ta.sub.2O.sub.5,
BaTa.sub.2O.sub.6, BaTiO.sub.3, TiO.sub.2, Sr(Zr,Ti)O.sub.3,
SrTiO.sub.3, PbTiO.sub.3, Al.sub.2O.sub.3, Si.sub.3N.sub.4, ZnS,
ZrO.sub.2, PbNbO.sub.3, and Pb(Zr,Ti)O.sub.3. It is preferred that
the material has a high dielectric constant and high resistance to
dielectric breakdown. The material can be light-scattering material
such as a sintered material, provided that the layer does not
prominently decrease the dielectric constant of the layer.
[0252] [Buffer Layer]
[0253] It is preferred that the material has a refractive index
equivalent to or higher than the refractive indexes of the
light-emitting layer and intermediate layer(s).
[0254] [Front Phosphor Layer]
[0255] Blue light(B)-emitting phosphor:
[0256] Excitable by UV: Sr.sub.2P.sub.2O.sub.7:Eu,
Sr.sub.5(PO.sub.4).sub.- 3Cl:Eu, SrS:Ce, SrGa.sub.2S.sub.4:Ce,
CaGa.sub.2S.sub.4:Ce
[0257] Green light(G)-emitting phosphor:
[0258] Excitable by UV: BaMg.sub.2Al.sub.16O.sub.27:Eu,Mn,
ZnS:Tb
[0259] Excitable by blue light: Y.sub.3Al.sub.5O.sub.12:Ce
[0260] Red light (R)-emitting phosphor:
[0261] Excitable by UV: Y(PV)O.sub.4, YVO.sub.4:Eu, ZnS:Sm,
(Ca,Sr)S:Eu
[0262] Excitable by blue light: (Ca,Sr)S:Eu
[0263] Light-scattering layer (W):
[0264] Excitable by blue light: Same as those for the production of
the light-scattering reflective layer
[0265] [Color Filter Layers (R, B, G)]
[0266] a color face plate for CRT, a light-conversion element plate
for duplication, a filter for mono-tube color television, a filter
for flat liquid crystal panel display, a filter for color solid
imaging device, those described in JP-A-8-20161
[0267] [Protecting Film]
[0268] light-transmitting film having a thickness of 1 to 50 .mu.m,
which may be provided with such functions as anti-reflection,
anti-staining property and anti-static property. Multi-layered
protecting film can be employed.
EXAMPLE 1
[0269] A white BaSO.sub.4-containing polyethylene terephthalate
(PET) sheet (thickness: 350 .mu.m) was prepared as a
light-scattering reflective opaque substrate. On the substrate was
coated a light-transmitting back electrode (thickness: approx. 10
.mu.m) comprising electroconductive particles of In.sub.2O.sub.3
and SnO.sub.2 dispersed in a resin by a screen-printing method.
[0270] Spherical particles (mean diameter: 1 .mu.m) of ZnS:Mn
phosphor were prepared by a spray heat-decomposing method. The
particles were then coated with a coat (mean thickness: 0.2 .mu.m)
of dielectric BaTiO.sub.3 material by a metal alkoxide
mixture-hydrolyzing method (see JP-A-6-200245) to give complex
phosphor particles. The complex phosphor particles and BaTiO.sub.3
super fine particles (mean diameter: 0.3 .mu.m) were dispersed in
an acrylic resin solution to give a dispersion (resin:phosphor
particles:BaTiO.sub.3 super fine particles=2:1:1, volume ratio).
The dispersion was coated on the light-transmitting electrode and
dried to give, a light-emitting layer (mean thickness: 10
.mu.m).
[0271] On a PET sheet (thickness: 10 .mu.m, a light-transmitting
protecting film) was formed an ITO electrode (thickness: 0.1 .mu.m,
a light-transmitting front electrode) by sputtering. The ITO
electrode of the PET film was then laminated on the
light-transmitting layer.
[0272] Thus, the dispersion EL device of the invention illustrated
in FIG. 4 was manufactured.
EXAMPLE 2
[0273] A white BaSO.sub.4-containing polyethylene terephthalate
(PET) sheet (thickness: 350 .mu.m) was prepared as a
light-scattering reflective opaque substrate. On the substrate was
coated a light-transmitting back electrode (thickness: approx. 10
.mu.m) comprising electroconductive particles of In.sub.2O.sub.3
and SnO.sub.2 dispersed in a resin by a screen-printing method.
[0274] Spherical particles (mean diameter: 1 .mu.m) of dielectric
BaTiO.sub.3 material were prepared by a spray heat-decomposing
method. The particles were then coated with a coat (mean thickness:
0.2 .mu.m) of ZnS:Mn phosphor by a MOCVD method (see WO 96/09353).
The coated particles were further coated with a coat of BaTiO.sub.3
by a metal alkoxide mixture-hydrolyzing method (see JP-A-6-200245)
to give complex phosphor particles. The complex phosphor particles
and BaTiO.sub.3 super fine particles (mean diameter: 0.3 .mu.m)
were dispersed in an acrylic resin solution to give a dispersion
(resin:phosphor particles:BaTiO.sub.3 super fine particles=2:1:1,
volume ratio). The dispersion was coated on the light-transmitting
electrode and dried to give a light-emitting layer (mean thickness:
10 .mu.m).
[0275] On a PET sheet (thickness: 10 .mu.m, a light-transmitting
protecting film) was formed an ITO electrode (thickness: 0.1 .mu.m,
a light-transmitting front electrode) by sputtering. The ITO
electrode of the PET film was then laminated on the
light-transmitting layer.
[0276] Thus, the dispersion EL device of the invention illustrated
in FIG. 5 was manufactured.
Utilization in Industry
[0277] By the use of the electroluminescence device of the
invention, it is able to extract a light emitted therein outside
with a high efficiency under the condition that the size of device
is the same as and the electric power required is the same as that
of the conventional electroluminescence device. Further, a
dispersion electroluminescence device of the invention shows an
increased emission efficiency in the extraction from the
light-emitting layer.
* * * * *